Improvement in balance slide-valves



UNITED STATES PATENT QFFICE.

THOMAS M. HERRIOTT AND SAMUEL MYERS, OF SOUTH PITTSBURG, PA.

IMPROVEMENT IN BALANCE SLIDE-VALVES.

Specification forming part of Letters Patent No. 84,278, dated November 24., 1868.

To all whom it may concern:

Be it known that we, THOMAS M. HERRIOTT and SAMUEL MYERs, of South Pittsburg, Allegheny county, State of Pennsylvania, have invented certain new and useful Improvements in the Construction of Balance Slide-Valves for Steam-Engines 5 and wehereby declare that the following is a full and exact description thereof, reference being had to tke accompanying drawings, which form part of this speciiication, and to the letters of reference marked on the drawings.

Our invention relates to that class of valves in which it is sought, by various arrangements, to shut off' the working-pressure from a sufficient area on the top of thevalve to substantially balance it.

Our invention consists in the mechanical construction of the valve itself, which may be used in steam-chests of the ordinary construction, the valve-seat and the cap ot' the steamchest being parallel, and the latter finished smooth, so as to make a `steam-joint with the top of the valve, as hereinafter explained.

In the drawings, Figure 1 isV a perspective view of our valve ready to be used in a suitable steam-chest. Fig. 2 is a vertical section of the same. Fig. 4 is a perspective of the packing-ring. Fig. 5 is a perspective of the spring-ring. Fig. 6 is a horizontal section of Fig. 5.

In all the figures the same letters indicate the same parts.

The working-face of our valve is not different from those in ordinary use, and is not shown except in section, Fig. 2,0 being the usual exhaust-passage. The parts which involve our invention are the cylindrical elevation or pro jection S, Figs. l and 2, the packing-ring C, Figs. 1, 2, and 4, and the spring-ring B, Figs. 1, 2, 5, and 6. e and f are a projection and slot' for connecting the valve-rod, and form no part of our invention.

The projection S rises at right angles with the face of the valve, so as to come within, say, one-sixteenth inch of the cap of the steamchest. Its diameter should be such that, together with C, it will present a horizontal area nearly equal to the face of the valve. The shoulder r at the base of S is beveled at an angle of about sixty degrees elevation, and the outside of the packing-ring has an equal inclination, as shown at r. The ring G should fit so as to move freely on the cylindrical elevation S.

The inside of the spring-ring B is beveled to correspond with the inclination of r and r', between which it fits, the surfaces in contact being ground steam-tight. The least inner diameter of B should be sufficient to allow it to close concentrically as far as the cut J J will permit. This cut will vary in dierent valves according to their size and extent of movement, and is closed against the passage of steam by the tongue c', which is attached to one end of the ring by rivet w, and laps over the inside of the other end, as shown at J, Figs. 5 and 6, the bevels at r and r being of sufficient width to lap over the tongue, and thus no steam is admitted to pass through the cuts J J. The proper vertical Width of B is p determined by the horizontal area of that part of' C which is in contact with the cap of' the steam-chest, and by the bevels of the angles 1 r. All these angles being, say, for comparison and illustration, forty-five degrees from a horizontal line, the width of B should be such that its total area be slightly greater than twice the area of the upper surface of C, and, in proportion as the angles r r' and the angle inside B are more obtuse, the area of its external surface must be increased, so that the concentric movement of B will be less than the vertical movement of C, in proportion as the area of C is less than one-half the total area of B, always giving a slight margin of' excess to the area of B, so as to always insure it (B) a slight excess of leverage as against O. From these data any competent mechanic can determine the relative proportions of any required valve.

The hole i through the body of the valve, from the top to the exhaust-passage, is intended to instantly relieve any pressure which might otherwise, through leakage of' the parts, or from other cause, accumulate on the top of the valve.

All its parts being thus constructed and arranged, as shown in Figs. 2 and l, our valve is complete and ready for use in a suitable steanrchest, and its operation is as follows, (the ring C being held in slight contactpwith the cap of the steam-chest by the elastic force of the ring B before steam is admitted k:)

Vhen steam is admitted to the elle-st, its pressure on the outside of B tends to close it coneentrically, and thus force upward C and maintain it in steam-tight contact With the cap 0f the chest7 thus cutting off steam communication With the top of the valve and establishing almost complete equilibrium of pressure upon both sides of the valve, and securing` the Well-known advantages of balanced valve.

If the valve should Wear by usage, the steampressure'on B will still render it effective.

In addition to' its advantages as regards efficiency, our valve has the further one of Very great simplicity and economy in its primary construction.

hat we claim as our invention, and desire to secure by Letters Patent, is-

The combination of the rings C and B with the projection S, the whole constructed substantially as-sliown and described.

T. M. HERRIOTT. SAMUEL MYERS. Vitnesses:

JonN G. STEPHENsoN, A. PATTERSON. 

